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We can use loops when we want to execute a part of code a certain number of times.


Here's an example:

for (initializing_variable; checking_condition; changing_variable_value)
//instructions to perform

See a 'for' loop example:

This example, for comparison purposes, shows two ways of printing ten numbers. It's obvious that loops greatly reduce the number of lines in the code: from ten we now have just two!

Look at the parenthesis in the first line of the loop:

  • int i = 1

A variable with the initial value of 1 was declared because we want to display the numbers from one (if you want to start from ten, it's enough to write int i = 10 in the same place).

You can name your variable any way you want but by convention it is 'i'” : you will for sure keep seeing it while reading about loops.

  • i <= 10

Next, there is a condition check: in our case we check if the „i” variable is less or equal 10 (because we want to print numbers including ten).

  •  i++

We change the value of the variable. '++' is an increment operator: it makes the value bigger by one. In the same place we could write the full operation: i = i + 1; it would also be correct. The effect would remain the same. But usually the shorthand is used.

Next, between the curly brackets, we write the instruction to be executed: we will print the 'i' variable incremented by one up to 10.




Task 1

Declare a range from 117 to 143 and print all the numbers in it.

Go to the first task:

Task 2

You can also count backwards. In that case the contents of the parentheses in the 'for' loop changes slightly: you enter the value to start from and where the loop must stop working. To illustrate it, code a New Year countdown: from 10 to 1 and then display the "Happy New Year!" message.

Example of the loop counting down::

for (int i = 20; i > 9; i--)

The countdown starts from 20. We count until 'i' is greater than 9 (that is, to 10), by decrementing the value of 'i' by one (similarly to how i++ was incrementing by one).

Go to the second task:

Task 3

Write a loop that executes seven times. Declare an int type variable with a value of 10. With each iteration the loop is to add 100 to that variable.

Go to the third task: